Microsoft Bookings allowing customers to double-book staff?

Because this booking page ignores both Outlook busy events and Bookings-native time off, have a Microsoft 365 administrator open a support request for a page-specific Bookings availability synchronization failure rather than recreating the staff member or service again.

Microsoft documents that:

• Bookable when staff are free should prevent bookings when assigned staff are unavailable.^1^
• With Events on Microsoft 365 calendar affect availability enabled, busy or tentative calendar periods should make the staff member unavailable.^2^
• Bookings-native time off should make the selected employee unavailable during that period.^3^

Your time-off test therefore fails documented behavior, while the comparable booking page still works. That points to an issue specific to this booking page or its calendar/free-busy synchronization.

Open the support request

1. Have a Microsoft 365 administrator open the Microsoft 365 admin center.
2. First go to Health → Service health and inspect:
   • Active incidents and advisories affecting Bookings, Exchange Online, or Microsoft 365.
   • Issue history for the date the behavior began.
     Service Support and Helpdesk administrators can also view service health.^4^
3. If no relevant incident appears, create a Microsoft 365 support request. A closely matching case—multiple booking pages suddenly ignoring staff calendar availability—was directed to Microsoft support for backend configuration and synchronization diagnostics.^5^

Include these details:

• The affected booking-page name and service name.
• Approximate date and time the problem started.
• One example Outlook event and one Bookings time-off entry that failed to block availability.
• Screenshots showing:
  • Staff → affected member → Events on Microsoft 365 calendar affect availability enabled.
  • Service → Availability options → Bookable when staff are free.
  • Only the intended staff member assigned.
  • The public booking page offering the conflicting slot.
• The working booking page used for comparison.
• A note that deleting/re-adding staff, recreating the service, resaving settings, and testing Bookings time off have already been completed.

Two checks worth recording before escalation

These do not repeat the configuration work already completed and can help support isolate the free/busy path:

1. Check calendar visibility
   • In Outlook on the web, the staff member opens Share → Calendar.
   • Under People inside your organization, set My Organization to Can view when I’m busy.
   • Save with Done.
     Microsoft lists this permission as necessary for Bookings to synchronize staff calendar availability.^6^
2. Create one controlled Outlook test
   • Put a short event on the staff member’s primary Microsoft 365 calendar.
   • Set Show as to Busy.
   • Test the exact interval from the public booking-page link.

Record whether the slot remains available. Even if that test succeeds, the failure of Bookings-native time off should still be included in the support request.

A multi-day-service limitation is documented in a Q&A case, but it only applies if this is a multi-day service. If it is, personal-calendar events may not be fully considered; otherwise, that workaround does not match this case.^7^

References

1. Configure service availability in Microsoft Bookings
2. Add team members to Bookings
3. Schedule business closures, time off, and vacation time
4. How to check Microsoft 365 service health
5. Bookings allowing people to book when staff are not available on their personal calendar - Microsoft Q&A
6. Shared Bookings Frequently Asked Questions (FAQ)
7. Does a Shared Bookings page consider staff availability from their Outlook calendar for multi-day services? - Microsoft Q&A